CVE-2025-5372: Libssh: incorrect return code handling in ssh_kdf() in libssh

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-04 · updated 2026-09-01
Weakness: CWE-682

Description

A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.

Affected products

libssh: before 0.11.2 — fixed in 0.11.2
Red Hat Enterprise Linux: 6.0, 7.0, 8.0, 9.0, 10.0
Red Hat OpenShift Container Platform 4.18: 4.0

How to fix

Upgrade to a fixed version: libssh 0.11.2. Check the vendor advisory for mitigations.

References

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